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Chris Cole b3d5255679 ARM: 8814/1: mm: improve/fix ARM v7_dma_inv_range() unaligned address handling 
[ Upstream commit a1208f6a82 ]

This patch addresses possible memory corruption when
v7_dma_inv_range(start_address, end_address) address parameters are not
aligned to whole cache lines. This function issues "invalidate" cache
management operations to all cache lines from start_address (inclusive)
to end_address (exclusive). When start_address and/or end_address are
not aligned, the start and/or end cache lines are first issued "clean &
invalidate" operation. The assumption is this is done to ensure that any
dirty data addresses outside the address range (but part of the first or
last cache lines) are cleaned/flushed so that data is not lost, which
could happen if just an invalidate is issued.

The problem is that these first/last partial cache lines are issued
"clean & invalidate" and then "invalidate". This second "invalidate" is
not required and worse can cause "lost" writes to addresses outside the
address range but part of the cache line. If another component writes to
its part of the cache line between the "clean & invalidate" and
"invalidate" operations, the write can get lost. This fix is to remove
the extra "invalidate" operation when unaligned addressed are used.

A kernel module is available that has a stress test to reproduce the
issue and a unit test of the updated v7_dma_inv_range(). It can be
downloaded from
http://ftp.sageembedded.com/outgoing/linux/cache-test-20181107.tgz.

v7_dma_inv_range() is call by dmac_[un]map_area(addr, len, direction)
when the direction is DMA_FROM_DEVICE. One can (I believe) successfully
argue that DMA from a device to main memory should use buffers aligned
to cache line size, because the "clean & invalidate" might overwrite
data that the device just wrote using DMA. But if a driver does use
unaligned buffers, at least this fix will prevent memory corruption
outside the buffer.

Signed-off-by: Chris Cole <chris@sageembedded.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2018-12-21 14:15:21 +01:00
arch ARM: 8814/1: mm: improve/fix ARM v7_dma_inv_range() unaligned address handling 2018-12-21 14:15:21 +01:00
block block/bio: Do not zero user pages 2018-12-19 19:19:50 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: do not free algorithm before using 2018-12-13 09:16:21 +01:00
Documentation x86/speculation: Provide IBPB always command line options 2018-12-05 19:32:04 +01:00
drivers net/mlx4_en: Fix build break when CONFIG_INET is off 2018-12-21 14:15:20 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs nfs: don't dirty kernel pages read by direct-io 2018-12-21 14:15:17 +01:00
include pstore/ram: Correctly calculate usable PRZ bytes 2018-12-17 09:24:39 +01:00
init sched/pelt: Fix warning and clean up IRQ PELT config 2018-12-19 19:19:49 +01:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel bpf: check pending signals while verifying programs 2018-12-21 14:15:21 +01:00
lib debugobjects: avoid recursive calls with kmemleak 2018-12-17 09:24:41 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/page_alloc.c: fix calculation of pgdat->nr_zones 2018-12-17 09:24:40 +01:00
net SUNRPC: Fix a potential race in xprt_connect() 2018-12-21 14:15:17 +01:00
samples samples: disable CONFIG_SAMPLES for UML 2018-10-11 02:15:46 +09:00
scripts scripts/spdxcheck.py: always open files in binary mode 2018-12-19 19:19:50 +01:00
security selinux: add support for RTM_NEWCHAIN, RTM_DELCHAIN, and RTM_GETCHAIN 2018-12-08 12:59:08 +01:00
sound ALSA: hda/realtek - Fix the mute LED regresion on Lenovo X1 Carbon 2018-12-17 09:24:42 +01:00
tools bpf: Fix verifier log string check for bad alignment. 2018-12-21 14:15:16 +01:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: arm64: Fix caching of host MDCR_EL2 value 2018-11-13 11:08:47 -08:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: Add Sasha as a stable branch maintainer 2018-12-01 09:37:25 +01:00
Makefile Linux 4.19.11 2018-12-19 19:19:54 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.